I have lost 2 rummy nose tetras in the last week to what looks like constipation, but I am starting to see similar symptoms on 2 other rummy nose tetras and 1 bolivian ram fry, so I doubt widespread constipation is the problem.

Symptoms: Weight loss, bulge in the body at the anus, with some black, stiff looking thread-like protrusions on one of the affected fish.

My tank parameters:
90 gallon tank set up in July of this year. I have been doing 50% water changes 2 times a week trying to get the upper hand on a major algae problem. I think I'm getting it under control. but still doing lots of big water changes. The tank is heavily planted with pressurized CO2, and I dose with Florish, nitrogen, phosphates, phosphorous, and potasium.

Temp 78 degrees
pH around 7 (varies a little with the water changes)
ammonia and nitrites 0
nitrates 5
Gh 8-9, KH 5-7 (tap water is gh 3, KH 2, but the Onyx substrate increases hardness)
I feed the fish New Life Spectrum pellets and sinking wafers

Well, that doesn't sound good. I have read the links you provided, and done a search on the web and of this site, and the symptoms certainly seem related. The only thing that doesn't quite match up is that the protrusions from the vent are very short, and in fact I had to look really closely to see them. They are also dark in color and appear stiff, more like bristles than dangling worms. I have emailed to get information about the meds, and also called my vet to see if he can get some for me. I am not optimistic, though - the treatment calls for 100% water change and thorough vacuuming of the substrate. I will probably have to nearly tear down my tank to accomplish this as it is heavily planted, and the stress of all this on my fish may be as bad as the worms! And of course I just added 5 new (and big enough to be kind of expensive) angelfish to my tank yesterday before I realized what was going on.....

Cathy - you're the best! Thanks for your help. The good news is that the bolivian fry are still in their own tank and so far show no signs of cross contamination. The one I spotted in the big tank is one of 2 that has survived on their own. Phew!

No luck with the Levamisole yet, but further searching took me to the website of National Fish Pharmaceuticals. I spoke on the phone with them, and they recommend their product Paracide D mixed with frozen food to treat the infested fish, and De-Los to treat the water to kill the eggs of the worms. Anyone have experience with any of these treatments?

Thanks Nancy - it's ordered and on its way! Did you use this to treat a different parasite in your tank? If so, can you tell me about the water change schedule you did with this medication or anything else I might need to know about how it is used?

Is this safe for use with invertebrates? I have snails and amano shrimp in this tank, and I understand the snails are intermediary carriers. Don't want the treatment to be fatal.

I don't know if the inverts would be safe, I used it with loaches so no inverts here (also tiger barbs & clown pleco). I know you need to leave the tank lights out, the levamisole will break down. You don't have to mix the entire amount, it'll keep much longer dry. The dosing has a very wide margin for error (very safe) so I divided the small amount of powder into four parts (by eye) & used 1/2 cup of water (appx 125 ml) to 1/4 of the drug. It makes enough for several treatments & keeps for ~3 months in the refrigerator after water is added, but the dry will keep even longer, at least a year in light blocking container in fridge.
As far as water changes go I did a thorough gravel vac after 48 hours to get any worms or eggs expelled. I repeated the dose then & again a week later but you may want to read more. The medical math,drug form, dose rates & various measurements (ppm, ml, teaspoon, mg, gal, lt) gets very, very confusing. At loaches.com forums do a search, shari2 has recently gathered a lot of the info together & chefkeith has a handy dose rate chart you can use. (just to give an example I have 1 teaspoon (5ml)/15gal as 1 dose = appx 3.5mg/L or 13.4mg/gal. I think that's the rate I used but I think it's higher than now recommended, as I recall 2mg(ppm)/liter).
Good luck.
Nancy
ps it didn't damage the biofilter & I'd read of people seeing worms in their filters so just remove any carbon & let the levamisole kill any "critters". The drug breaks down in ~48 hours so you don't really need to worry about using carbon at the end of each treatment unless you want.

Well, things aren't looking so good this morning. As Nancy indicated, the dosing is very confusing, so I dosed the medication at the rate suggested in this article, which indicates 5 mg of pure levamisole hydrochloride per 100 gallons of tank water:

I expected some losses as some of the fish seem to be very sick from the worms, but they all look pretty bad this morning. The rummy nose tetras are very pale and are flashing on the bottom of the tank. My harlequin rasboras are a little listless, and the ones bloated from the worms are developing ulcers on their body by their dorsal fin. I can still see worms hanging from some of the vents. Even my brand new angels are listless and hanging out at the bottom of the tank. No one is eating. Only the snails seem unaffected.

I am worried that the medication is compounding the problem, but can't know for sure. Any additional advice would be appreciated!

Uh oh, how did you measure the 5mg? I'll try to help but I'm not sure I understand, did you dilute the entire amount of powder (20.17g) in 500ml water? (or 1/4 of the powder in 125ml (appx 1/2cup)? I'm worried about the decimal point, it's easy to get confused so don't be insulted, By my calculations you should have used something close to 3.5 teaspoons of the diluted solution (powder mixed in water) Does that sound like what you did?

It could be the fish are so heavily infested +/or weakened that even if the parasites are killed they are having trouble expelling them. If you did dry powder, by chefkeith's calculator I think 0.17 teaspoons is right but I'm not sure. If either doesn't sound close to what you did you need to change lots of water, although I have seen dosing as high as 8mg/liter so there's lots of leeway. Good luck.
Nancy

Based on the article I cited which stated you use 5 grams of dry powder to treat 100 gallons of water (sorry - I just noticed in my last post I said 5 mg, but the article recommends 5 grams, which is what I used), I mixed the entire 20.17 grams of powder in 500 ml of declorinated water, then added 1/4 of that total mixture (125 ml) to the tank.

It sounds like you dosed at a much lower (and probably correct!) rate. I'm going to do a huge water change right now and see if it helps. I agree that some of my fish are probably so heavily infested that there is no saving them. I am very worried about my brand new angel fish - they have not been in the tank long enough to be showing such signs of distrest from infestation, which is what makes me think I gave them a huge overdose of medication.

Thanks so much for helping me figure this out. I have a feeling I'm going to lose this whole tank of fish, especially now that I've probably poisoned them with an overdose of medication!